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Visar resultat 1 - 5 av 26 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Predicting and optimising acoustical and vibrational performance of open porous foams

   Författare :Eleonora Lind; Peter Göransson; Wim Desmet; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; porous material; foam; Biot; optimisation; tortuosity; permeability; Acoustics; Akustik;

   Sammanfattning : This thesis concerns the modelling of acoustical and vibrational properties of open cell porous foams in multi-layered structures, especially multi-layered panels. The object is to enable optimisation of the microscopic geometry of the foam with respect to macroscopic quantities such as sound pressure level, surface velocity, total mass or cost. LÄS MER

3. 2. Nuclear magnetic resonance studies of water self-diffusion in porous systems

   Författare :Daniel Topgaard; Fysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diffusion diffraction; nonfreezing; anisotropy; tortuosity; cross relaxation; emulsion; starch; cellulose; porous material; water; NMR; self-diffusion; Physical chemistry; Fysikalisk kemi;

   Sammanfattning : Proton nuclear magnetic resonance (NMR) was used to study the self-diffusion of water in porous systems that respond to a change in water content in order to elucidate the porous structure and the properties of the confined water. In the carbohydrate systems cellulose fibers and starch granules, water is free to move throughout the porous objects, albeit with a rate reduced from the value of the bulk liquid, The reduction is related to the tortuosity of the pore space filled by water. LÄS MER

4. 3. Microstructure in SOFC: electrochemical simulations and experiments

   Författare :Xiaoqiang Zhang; Värmeöverföring; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Solid oxide fuel cell; Electrochemical impedance spectroscopy; 3D reconstruction; Tortuosity; Electrochemical kinetics; Multiphysics; Thermal stress;

   Sammanfattning : Solid oxide fuel cells (SOFCs) are highly efficient and environmentally friendly power sources that convert chemical energy directly into electricity and heat, without the need for combustion. Despite their many benefits, the performance and durability of SOFCs heavily depend on the quality of their porous anode and cathode components. LÄS MER

5. 4. On Diffusion Transport Properties in Fuel Cell Gas Diffusion Layers Using the Lattice Boltzmann Method

   Författare :Mayken Espinoza Andaluz; Värmeöverföring; []
   Nyckelord :PEFC; lattice Boltzmann method; gas diffusion layers; porosity; Gas-phase tortuosity; permeability; inertial coefficient; diffusibility; pore-scale modeling;

   Sammanfattning : The polymer electrolyte fuel cell (PEFC) is considered as one of the most promising devices for providing efficient, clean and noiseless conversion of chemical energy to electrical energy. This device can provide electrical and thermal energy for transport, mobile and stationary applications ranging in a wide range of power requirements. LÄS MER

7. 5. On Microstructural Analysis of Porous Media Existing in Fuel Cells Using the Lattice Boltzmann Method

   Författare :Mayken Espinoza Andaluz; Värmeöverföring; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Porous media; lattice Boltzmann method; microscale; Gas-phase tortuosity; Porosity; Fuel Cell;

   Sammanfattning : This Licentiate thesis aims to gain understanding related to the fluid behavior in porous media existent in fuel cells (FCs) at microscale. In order to achieve this; the widely used methodology for solving problems in porous media has been applied, the Lattice Boltzmann Method (LBM). LÄS MER